I. Field of the Invention
The present invention relates to fasteners and more particularly, to a fastener with a self-heading stud and screw rivet.
II. Description of the Prior Art
There are a number of previously known self-heading bolts particularly adapted for securement in a hole which is accessible from only one side. Two such self-heading bolts are disclosed in British Pat. Nos. 12,795 and 567,274.
These previously known self-heading bolts typically include four separable pieces, namely, a threaded shank having an enlarged head formed on one end, a sleeve, a washer, and a nut. The sleeve and washer are first mounted over the shank after which a nut threadably engages the shank. Then the shank is inserted through a hole in a workpiece. Rotation of the nut while holding the shank fast draws the enlarged head into and deforms the sleeve and prevents the retraction of the sleeve and shank from the hole.
These previously known self-heading bolts, however, are disadvantageous in a number of different respects, including control and ease of installation and fastening ability. First, due to the four separable components for each self-heading bolt, the assembly of the self-heading bolt is unnecessarily time-consuming and the resultant assembly is difficult to install, particularly when the hole is hard to reach. Moreover, due to the multiplicity of the components, individual components are prone to and easily become lost prior to the installation.
A still further disadvantge of these previously known self-heading bolts is that the sleeve must necessarily be made of a relatively malleable material so that the enlarged head of the shank can easily deform it. Due to its malleability, however, the upper end of the sleeve is oftentimes drawn into or between the nut and shank threads when a high torque is applied on the nut. This, of course, adversely affects the torque-clamp load relationship, destroys the sleeve, and oftentimes requires replacement of the entire self-heading bolt.
A still further disadvantage of these previously known self-heading bolts is that the bolt itself is not secured in the hole or holes, but rather only the retraction of the bolt from the hole is prevented by the deformed sleeve. Consequently, upon removal of the nut from the shank, the shank can easily fall through the blind hole and become lost and require a new sleeve and a new bolt.